Yeah, I've seen those straw men. What I am still waiting to see are lists of the top 50 sporting events in any given year. My thought is any such list will mirror the chart you provided that runs from 1986; i.e., relative to events that draw higher ratings, the Indy 500 will remain where it basically always has. No revelation there.
-The Nothing To See Here Folks Disciple of INDYCAR